[...] How do I go about joining in on training and events, do I just join the Teamspeak shortly before the event? Also, could you accept my request to join the steam group?

Yes, that's pretty much it. We do post announcements on the group if there is a training or an event 1 hour and 5 minutes before they start. Warmup to events usually starts 30 minutes before an event, so you might want to join early to those.